Non-perturbative Interband Response of InSb Driven Off-resonantly by Few-cycle Electromagnetic Transients

TL;DR

This paper investigates the non-perturbative interband response of bulk InSb when driven by intense, off-resonant multi-THz pulses, revealing unexpected temporal structures and Rabi flopping effects.

Contribution

It demonstrates that high-field, off-resonant multi-THz pulses induce non-perturbative interband dynamics in InSb, evidenced by experimental observations and quantum simulations.

Findings

Observation of temporal substructure in nonlinear signals

Evidence of Rabi flopping in off-resonant excitation

Non-perturbative interband response at high field amplitudes

Abstract

Intense multi-THz pulses are used to study the coherent nonlinear response of bulk InSb by means of field-resolved four-wave mixing spectroscopy. At amplitudes above 5 MV/cm the signals show a clear temporal substructure which is unexpected in perturbative nonlinear optics. Simulations based on a two-level quantum system demonstrate that in spite of the strongly off-resonant character of the excitation the high-field pulses drive the interband resonances into a non-perturbative regime of Rabi flopping.